There is no harm to running 10/3 rather than 10/2, but unless your machines
actually require a neutral you don't have to.

You have not mentioned what the machines draw, but unless they are huge 30a
should be plenty; I run both of mine on 20a.

You will have to use receptacles rated for 30a, but other than that it seems
pretty straight forward.(though I would rather see two 20a circuits..)